There is illumination using a solid-state light source such as a laser. Under such illumination, a phosphor is irradiated with blue light emitted from the solid-state light source to generate white light. The phosphor scatters yellow light excited by a part of the blue light and the transmitted other part of the blue light, so that the white light can be generated by mixing the yellow light and the blue light.
Furthermore, the solid-state light source such as a laser has strong directivity and high energy density. Therefore, when the phosphor is directly irradiated with blue light emitted from the solid-state light source, the phosphor generates a lot of heat in an irradiated area and increases in temperature. Since the phosphor has a temperature quenching property in which the wavelength conversion efficiency of the phosphor decreases with increase of the temperature of the phosphor, it is necessary to suppress the temperature increase of the phosphor.
Therefore, Patent Literature 1 discloses a lighting apparatus in which diffusing means for diffusing light from a solid-state light source is formed on a phosphor layer. According to Patent Literature 1, an energy distribution of light from the solid-state light source is diffused by the diffusing means, so that energy concentration on the phosphor layer can be prevented (thermal load can be reduced), and temperature increase of the phosphor layer can be suppressed.